Add OutPacket interface and ByteBuf implementation

Replacement for LittleEndianWriter, GenericLittleEndianWriter,
and MaplePacketLittleEndianWriter.

src/main/java/net/packet/OutPacket.java

@@ -1,4 +1,20 @@
 package net.packet;
 
+import java.awt.*;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+
 public interface OutPacket extends Packet {
+    Charset STRING_CHARSET = StandardCharsets.US_ASCII;
+
+    void writeByte(byte value);
+    void writeByte(int value);
+    void writeBytes(byte[] value);
+    void writeShort(short value);
+    void writeInt(int value);
+    void writeLong(long value);
+    void writeBoolean(boolean value);
+    void writeString(String value);
+    void writePoint(Point value);
+    void skip(int numberOfBytes);
 }